The Panama Canal

The Panama Canal

The Panama Canal  is a 77.1-kilometre (48 mi) ship canal in Panama that connects the Atlantic Ocean (via the Caribbean Sea) to thePacific Ocean. The canal cuts across the Isthmus of Panama and is a key conduit for international maritime trade. There are locks at each end to lift ships up toGatun Lake, an artificial lake created to reduce the amount of excavation work required for the canal, 26 metres (85 ft) above sea level. The current locks are 33.5 metres (110 ft) wide. A third, wider lane of locks is currently under construction and is due to open in 2016.

France began work on the canal in 1881, but had to stop because of engineering problems and high mortality due to disease. The United States took over the project in 1904, and took a decade to complete the canal, which was officially opened on August 15, 1914. One of the largest and most difficult engineering projects ever undertaken, the Panama Canal shortcut greatly reduced the time for ships to travel between the Atlantic and Pacific Oceans, enabling them to avoid the lengthy, hazardous Cape Horn route around the southernmost tip of South America via the Drake Passage or Strait of Magellan. The shorter, faster, and safer route to the U.S. West Coast and to nations in and around the Pacific Ocean allowed those places to become more integrated with the world economy. It takes between 20 and 30 hours to traverse the canal. The Panama Canal had its 100-year anniversary on August 15, 2014.

During construction, ownership of the territory that is now the Panama Canal was first Colombian, then French, and then American. The US continued to control the canal and surrounding Panama Canal Zone until the 1977 Torrijos–Carter Treaties provided for handover to Panama. After a period of joint American–Panamanian control, the canal was taken over by the Panamanian government in 1999, and is now managed and operated by the Panama Canal Authority, a Panamanian government agency.

Annual traffic has risen from about 1,000 ships in 1914, when the canal opened, to 14,702 vessels in 2008, the latter measuring a total of 309.6 million Panama Canal/Universal Measurement System (PC/UMS) tons. By 2008, more than 815,000 vessels had passed through the canal; the largest ships that can transit the canal today are called Panamax.^[1] The American Society of Civil Engineers has named the Panama Canal one of the seven wonders of the modern world.

The Golden Gate Bridge

The Golden Gate Bridge

The Golden Gate Bridge is a suspension bridge spanning the Golden Gate strait, the mile-wide, three-mile-long channel between San Francisco Bay and the Pacific Ocean. The structure links the U.S. city of San Francisco, on the northern tip of the San Francisco Peninsula, to Marin County, bridging both U.S. Route 101 and California State Route 1 across the strait. The bridge is one of the most internationally recognized symbols of San Francisco, California, and the United States. It has been declared one of the Wonders of the Modern World by the American Society of Civil Engineers.^[7]

The Frommers travel guide considers the Golden Gate Bridge "possibly the most beautiful, certainly the most photographed, bridge in the world".^[8] It opened in 1937 and had, until 1964, the longest suspension bridge main span in the world, at 4,200 feet (1,300 m).

The Delta Works

The Delta Works

The Delta Works is a series of construction projects in the southwest of the Netherlands to protect a large area of land around the Rhine-Meuse-Scheldt delta from the sea. The works consist of dams, sluices, locks, dykes, levees, and storm surge barriers. The aim of the dams, sluices, and storm surge barriers was to shorten the Dutch coastline, thus reducing the number of dikes that had to be raised.

Along with the Zuiderzee Works, Delta Works have been declared one of the Seven Wonders of the Modern World by the American Society of Civil Engineers.

The Empire State Building

              

The Empire State Building

                 

 The Empire State Building is a 103-story skyscraper located in Midtown Manhattan, New York City, at the intersection of Fifth Avenue and West 34th Street. It has a roof height of 1,250 feet (380 m), and with its antenna spire included, it stands a total of 1,454 feet (443 m) high.^[6] Its name is derived from the nickname for New York, theEmpire State. It stood as the world's tallest building for nearly 40 years, from its completion in early 1931 until the topping out of the original World Trade Center's North Tower in late 1970.^[12] Following the September 11 attacks in 2001, the Empire State Building was again the tallest building in New York (although it was no longer the tallest in the US or the world), until One World Trade Center reached a greater height on April 30, 2012.^[13] The Empire State Building is currently the fourth-tallest completed skyscraper in the United States (after the One World Trade Center, the Willis Tower and Trump International Hotel and Tower, both in Chicago), and the 23rd-tallest in the world (the tallest now is Burj Khalifa, located in Dubai). It is also the fifth-tallest freestanding structure in the Americas.

The Empire State Building is generally thought of as an American cultural icon. It is designed in the distinctive Art Deco style and has been named as one of the Seven Wonders of the Modern World by the American Society of Civil Engineers. The building and its street floor interior are designated landmarks of the New York City Landmarks Preservation Commission, and confirmed by the New York City Board of Estimate.^[14] It was designated as a National Historic Landmark in 1986.^[10][15][16] In 2007, it was ranked number one on the AIA's List of America's Favorite Architecture.

The building is owned by the Empire State Realty Trust, for which Anthony Malkin serves as Chairman, CEO and President.^[17] In 2010, the Empire State Building underwent a $550 million renovation, with $120 million spent to transform the building into a more energy efficient and eco-friendly structure.^[18] Receiving a goldLeadership in Energy and Environmental Design (LEED) rating in September 2011, the Empire State Building is the tallest LEED certified building in the United States.

The Itaipu Dam

The Itaipu Dam

The Itaipu Dam  Portuguese pronunciation: [itɐjˈpu], locally: [ita.iˈpu], Spanish pronunciation: [itaiˈpu]) is a hydroelectric damon the Paraná River located on the border between Brazil and Paraguay. The name "Itaipu" was taken from an isle that existed near the construction site. In the Guaraní language, Itaipu means "the sounding stone".

The dam is the largest operating hydroelectric facility in terms of annual energy generation, generating 98.3 TWh in 2012 and 98.6 TWh in 2013, while the annual energy generation of the Three Gorges Dam was 98.1 TWh in 2012 and 83.7 TWh in 2013.^[1] It is a binational undertaking run by Brazil and Paraguay at the Paraná River on the border section between the two countries, 15 km (9.3 mi) north of the Friendship Bridge. The project ranges from Foz do Iguaçu, in Brazil, and Ciudad del Este in Paraguay, in the south to Guaíra and Salto del Guairá in the north. The installed generation capacity of the plant is 14 GW, with 20 generating units providing 700 MW each with a hydraulic design head of 118 m. In 2013 the plant generated a record 98.6 TWh, supplying approximately 75% of the electricity consumed by Paraguay and 17% of that consumed by Brazil.^[1]

Of the twenty generator units currently installed, ten generate at 50 Hz for Paraguay and ten generate at 60 Hz for Brazil. Since the output capacity of the Paraguayan generators far exceeds the load in Paraguay, most of their production is exported directly to the Brazilian side, from where two 600 kV HVDC lines, each approximately 800 km long, carry the majority of the energy to the São Paulo/Rio de Janeiro region where the terminal equipment converts the power to 60 Hz.

CN Tower

CN Tower

                            The CN Toweris a 553.33 m-high (1,815.4 ft) concrete communications and observation tower in Downtown Toronto, Ontario, Canada.^[3][6] Built on the former Railway Lands, it was completed in 1976, becoming the world's tallest free-standing structure and world's tallest tower at the time. It held both records for 34 years until the completion of Burj Khalifa and Canton Tower in 2010. It remains the tallest free-standing structure in the Western Hemisphere, a signature icon of Toronto's skyline, and a symbol of Canada, attracting more than two million international visitors annually.^[5][9]

Its name "CN" originally referred to Canadian National, the railway company that built the tower. Following the railway's decision to divest non-core freight railway assets, prior to the company's privatization in 1995, it transferred the tower to the Canada Lands Company, a federal Crown corporation responsible for real estate development. Since the name CN Tower became common in daily usage, the abbreviation was eventually expanded to Canadian National Tower or Canada's National Tower. However, neither of these names is commonly used.^[10]

In 1995, the CN Tower was declared one of the modern Seven Wonders of the World by the American Society of Civil Engineers. It also belongs to the World Federation of Great Towers, where it holds second-place ranking.

Channel Tunnel

Channel Tunnel

             The Channel Tunnel (French: Le tunnel sous la Manche; also referred to as the Chunnel)^[2][3] is a 50.5-kilometre (31.4 mi) rail tunnel linking Folkestone, Kent, in the United Kingdom, with Coquelles, Pas-de-Calais, near Calais in northern France, beneath the English Channel at the Strait of Dover. At its lowest point, it is 75 m (250 ft) deep.^[4][5][6] At 37.9 kilometres (23.5 mi), the tunnel has the longest undersea portion of any tunnel in the world, although the Seikan Tunnel in Japan is both longer overall at 53.85 kilometres (33.46 mi) and deeper at 240 metres (790 ft) below sea level. The speed limit in the tunnel is 160 kilometres per hour (99 mph).^[7]

The tunnel carries high-speed Eurostar passenger trains, the Eurotunnel Shuttle for automobiles and other road vehicles—the largest^[8] such transport in the world—and international rail freight trains.^[9] The tunnel connects end-to-end with the LGV Nord and High Speed 1 high-speed railway lines.

Ideas for a cross-Channel fixed link appeared as early as 1802,^[10][11] but British political and press pressure over compromised national security stalled attempts to construct a tunnel.^[12] An early attempt at building a Channel Tunnel was made in the late 19th century, on the English side "in the hope of forcing the hand of the English Government".^[13] The eventual successful project, organised by Eurotunnel, began construction in 1988 and opened in 1994. At £4.650 billion, the project came in 80% over its predicted budget.^[14] Since its construction, the tunnel has faced several problems. Fires and cold weather have both disrupted operation of the tunnel.^[15][16]Illegal immigrants have attempted to use the tunnel to enter the UK,^[17] causing a minor diplomatic disagreement over the siting of the Sangatte refugee camp, which was eventually closed in 2002.

earthquake

Earthquark

                 An earthquake (also known as a quake, tremor or temblor) is the result of a sudden release of energy in the Earth's crust that creates seismic waves. Theseismicity, seismism or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time.

Earthquakes are measured using observations from seismometers. The moment magnitude is the most common scale on which earthquakes larger than approximately 5 are reported for the entire globe. The more numerous earthquakes smaller than magnitude 5 reported by national seismological observatories are measured mostly on the local magnitude scale, also referred to as the Richter scale. These two scales are numerically similar over their range of validity. Magnitude 3 or lower earthquakes are mostly almost imperceptible or weak and magnitude 7 and over potentially cause serious damage over larger areas, depending on their depth. The largest earthquakes in historic times have been of magnitude slightly over 9, although there is no limit to the possible magnitude. The most recent large earthquake of magnitude 9.0 or larger was a 9.0 magnitude earthquake in Japan in 2011 (as of March 2014), and it was the largest Japanese earthquake since records began. Intensity of shaking is measured on the modified Mercalli scale. The shallower an earthquake, the more damage to structures it causes, all else being equal.^[1]

At the Earth's surface, earthquakes manifest themselves by shaking and sometimes displacement of the ground. When the epicenter of a large earthquake is located offshore, the seabed may be displaced sufficiently to cause a tsunami. Earthquakes can also trigger landslides, and occasionally volcanic activity.

In its most general sense, the word earthquake is used to describe any seismic event — whether natural or caused by humans — that generates seismic waves. Earthquakes are caused mostly by rupture of geological faults, but also by other events such as volcanic activity, landslides, mine blasts, and nuclear tests. An earthquake's point of initial rupture is called its focus or hypocenter. The epicenter is the point at ground level directly above the hypocenter.

Tsunami

Tsunami

               A tsunami (plural: tsunamis or tsunami; from Japanesepronunciation also known as a seismic sea wave, is a series of water waves caused by the displacement of a large volume of a body of water, generally an ocean or a large lake. Earthquakes, volcanic eruptions and other underwater explosions (including detonations of underwater nuclear devices), landslides, glacier calvings,meteorite impacts and other disturbances above or below water all have the potential to generate a tsunami.

Tsunami waves do not resemble normal sea waves, because their wavelength is far longer. Rather than appearing as a breaking wave, a tsunami may instead initially resemble a rapidly rising tide, and for this reason they are often referred to as tidal waves. Tsunamis generally consist of a series of waves with periodsranging from minutes to hours, arriving in a so-called "wave train".^[4] Wave heights of tens of metres can be generated by large events. Although the impact of tsunamis is limited to coastal areas, their destructive power can be enormous and they can affect entire ocean basins; the 2004 Indian Ocean tsunami was among the deadliest natural disasters in human history with at least 290,000 people killed or missing in 14 countries bordering the Indian Ocean.

The Greek historian Thucydides suggested in his late-5th century BC History of the Peloponnesian War, that tsunamis were related to submarine earthquakes,^[5][6] but the understanding of a tsunami's nature remained slim until the 20th century and much remains unknown. Major areas of current research include trying to determine why some large earthquakes do not generate tsunamis while other smaller ones do; trying to accurately forecast the passage of tsunamis across the oceans; and also to forecast how tsunami waves would interact with specific shorelines.

Tsunamis are often referred to by the inaccurate and highly misleading term tidal wave, although the phenomenon is unrelated to the tides.

Snow

Snow

หิมะ เป็นรูปหนึ่งของการตกลงมาของน้ำจากบรรยากาศ อยู่ในรูปของผลึกน้ำแข็งจำนวนมากเรียก เกล็ดหิมะ จับตัวรวมกันเป็นก้อน ดังนั้นหิมะจึงมีเนื้อที่หยาบเป็นเกล็ด และมีโครงสร้างที่กลวงจึงมีความนุ่มเมื่อสัมผัส

หิมะนั้นเกิดจากละอองน้ำเกิดการเกาะรวมตัวกันในชั้นบรรยากาศที่อุณหภูมิต่ำว่า 0 °C (32 °F) และตกลงมา นอกจากนี้หิมะยังสามารถผลิตได้จากเครื่องสร้างหิมะเทียม (snow cannon)

รูปลักษณะของเกล็ดหิมะ

คำอธิบายถึงความสมมาตรของเกล็ดหิมะนั้นโดยทั่วไป มีอยู่ 2 คำอธิบาย คือความสมมาตรของส่วนที่ยื่นออกมาของเกล็ดหิมะนั้น จะเป็นสมมาตรแบบหกด้านเสมอ เนื่องมาจากเกล็ดน้ำแข็งปกตินั้นมีโครงสร้างผลึกหกเหลี่ยม (หรือที่รู้จักกันในชื่อ ice I_h) บนระนาบฐาน (basal plane)

1. อาจเป็นไปได้ที่จะมีการสื่อสารหรือแลกเปลี่ยนข้อมูลระหว่างส่วนที่ยื่นออกของเกล็ดหิมะ ซึ่งส่งผลให้การงอกออกของแต่ละก้านนั้นส่งผลถึงกัน ตัวอย่างของรูปแบบที่ใช้ในการสื่อสารนั้นอาจเป็น ความตึงผิว หรือ โฟนอน (phonon)
2. คำอธิบายที่สองนี้จะค่อนข้างแพร่หลายกว่า คือ แต่ละก้านของเกล็ดหิมะนั้นจะงอกออกโดยไม่ขึ้นแก่กัน ในสภาพแวดล้อมที่อุณหภูมิ ความชื้น และสภาพแวดล้อมอื่น ๆ นั้นมีการเปลี่ยนแปลงอย่างรวดเร็ว แต่เมื่อเทียบกับขนาดของเกล็ดหิมะแล้วเชื่อว่าสภาพแวดล้อมจะมีสภาพที่เหมือนกันในช่วงขนาดสเกลของเกล็ดหิมะ ซึ่งส่งผลให้การงอกออกของก้านในแต่ละด้านนั้นอยู่ภายใต้เงื่อนไขเหมือนกัน จึงทำให้ลักษณะการงอกออกนั้นเหมือนกัน ในลักษณะเดียวกับที่รูปแบบการเติบโตของวงแหวนอายุในแกนของต้นไม้ในสภาพแวดล้อมเดียวกันจะมีรูปร่างเหมือน ๆ กัน ความแตกต่างของสภาพแวดล้อมที่ระดับสเกลใหญ่กว่าเกล็ดหิมะนั้นส่งผลให้รูปของเกล็ดหิมะแต่ละเกล็ดนั้นมีรูปร่างที่แตกต่างกัน และหิมะเกิดจากการละอองน้ำในอากาศที่แปรสภาพเป็นของแข็งเพราะอุณหภูมิต่ำ

อย่างไรก็ตาม แนวความคิดที่ไม่มีเกล็ดหิมะใดที่มีรูปร่างเหมือนกันนั้นไม่ถูกต้อง เกล็ดหิมะสองเกล็ดนั้นมีโอกาสเหมือนกันได้ เพียงแต่โอกาสนั้นน้อยมาก American Meteorological Societyได้บันทึกการค้นพบเกล็ดหิมะที่มีรูปร่างเหมือนกันโดย แนนซี่ ไนท์ (Nancy Knight) ซึ่งทำงานที่National Center for Atmospheric Research ผลึกที่ค้นพบนั้นไม่เชิงเป็นเกล็ดหิมะซะทีเดียวที่เป็นรูป ปริซึมหกเหลี่ยมกลวง (hollow hexagonal pris )

"Snowfall" redirects here. For other uses, see Snow (disambiguation) and Snowfall (disambiguation).

The process of precipitating snow is called snowfall. Snowfall tends to form within regions of upward movement of air around a type of low-pressure system known as anextratropical cyclone. Snow can fall poleward of these systems' associated warm fronts and within their comma head precipitation patterns (called such due to the comma-like shape of the cloud and precipitation pattern around the poleward and west sides of extratropical cyclones). Where relatively warm water bodies are present, for example because of water evaporation from lakes, lake-effect snowfall becomes a concern downwind of the warm lakes within the cold cyclonic flow around the backside of extratropical cyclones. Lake-effect snowfall can be heavy locally. Thundersnow is possible within a cyclone's comma head and within lake effect precipitation bands. In mountainous areas, heavy snow is possible where upslope flow is maximized within windward sides of the terrain at elevation, if the atmosphere is cold enough. Snowfall amount and its related liquid equivalent precipitation amount are measured using a variety of different rain gauges.Snow is precipitation in the form of flakes of crystalline water ice that falls from clouds. Since snow is composed of small ice particles, it is a granular material. It has an open and therefore soft, white, and fluffy structure, unless subjected to external pressure. Snowflakes come in a variety of sizes and shapes. Types that fall in the form of a ball due to melting and refreezing, rather than a flake, are known as hail, ice pellets or snow grains.

Computer Network

Computer Network

A computer network is a group of computers connected to each other electronically. This means that the computers can "talk" to each other and that every computer in the network can send information to the others. Usually, this means that the speed of the connection is fast - faster than a normal connection to the Internet. Some basic types of computer networks include:

·         A local area network (often called a LAN) connects two or more computers, and may be called a corporate network in an office or business setting.

·         An "Internetwork", sometimes called a Wide Area Network (because of the wide distance between networks) connects two or more smaller networks together. The largest internetwork is called the Internet.

Computers can be part of several different networks. Networks can also be parts of bigger networks. The local area network in a small business is usually connected to thecorporate network of the larger company. Any connected machine at any level of the organization may be able to access the Internet, for example to demonstrate computers in the store, display its catalogue through a web server, or convert received orders into shipping instructions.

Microsoft Windows, Linux and most other operating systems use TCP/IP for networking. Apple Macintosh computers used Appletalk in the past, but it uses TCP/IP now.

To set up a network an appropriate media is required. This can be wired or wireless. Twisted-pair, co-axial or fiber-optic are examples of cable and infra-red, blue-tooth, radio-wave, micro-wave etc. are wireless media used for networking. When you are working with a mere LAN, computers, media and peripherals are sufficient. But when you are working with a wider range you have use some additional devices like bridge, gateway or router to connect different small or large networks. And obviously a protocol must be maintained.

To set up a network you have to select an appropriate topology to arrange the hardware devices using the media. Topologies generally used are bus-topology, ring-topology, star-topology, tree-topology, object-oriented topology etc. Among these star-topology and tree-topology are most popular nowadays.